1) Field of the Invention
The present invention relates to a sheet carrier apparatus in an image forming apparatus.
2) Description of the Related Art
In general, an image forming apparatuses such as a copying machine includes a sheet carrier apparatus or the like. Some sheet carrier apparatuses include a carrier guide, and carry a sheet by sliding the sheet on the carrier guide.
Recently, resources saving and cost control have been required and the image forming apparatus comes to form an image on a backing paper, which has an image on a back side, or a recycled paper.
However, several problems occur when the backing paper or the recycled paper are used. For example, such papers tend to produce paper dust during a transport process, and the paper dust accumulates on the carrier guide. Particularly, when the carrier guide has a curved portion, the sheet bumps or rubs against the carrier guide, or is bent due to the curved portion. Therefore, the amount of the paper dust increases.
When the paper dust accumulates on the carrier guide, the paper dust adheres to the sheet again while the sheet is being carried, and a coefficient of friction of a carrier roller pair decreases. Consequently, the sheet is not carried correctly.
In the case of the image forming apparatus such as an electrophotographic image forming apparatus, if the paper dust adheres to the sheet again during transportation of the sheet, and enters into a printer engine, the paper dust may adhere to an image carrier (a photoconductor or an intermediate transfer belt). Moreover, a cleaning apparatus, which is arranged near the image carrier, may fail to remove the paper dust completely. Consequently, the image forming apparatus forms abnormal images, such as an image that has black lines and white lines, or an image that has white spots and black spots.
Japanese Patent Application Laid-open No. H7-215523 discloses a carrier guide that includes a hole through which the paper dust falls while the sheet is being carried. However, some paper dust still remains on the sheet, and such paper dust may drop or accumulate in other transport paths undesirably. Consequently, the paper dust is built up inside the image forming apparatus, and an increase of skew or slip ratio deteriorates transport performance.